Testing clamp



Jan. 17, 192s.

H. L. SCOTT TESTING CLAMP Filed Nov. 25,

amm

Henry 5002? a/mw/ Patented Jan.' 17, 192e.

PATENT OFFICE. y y

HENRY Lfsoo'r'r, or EnovIDENcE, RHoDE ISLAND, AssrGNon, BY MEsNEAssIGN- MENTS, To HENRYV :..soo'r'r COMPANY, oF rEovrnENcE, RHonE ISLAND, A co1?.-

PORATIGN OF :RHODEISLAN D.

'rnsjrrNG enzima` "'applicationnleanoveinber 25,1921. seriai No. 517,731.

j This invention relates to improvements inthe construction. of specimen-gripping clamps employed in machines forf testing the strength or stretch of materials, and has for i its object" to provide in combination with such at clamp an auxiliary clamp weight memberl for Vexerting a preliminary tension on a specimen prior to the olosingfof the jaws of the main clamp uponj'itf j f 1 "further `object ,ofV thejinvention is to providea"jaw ygripping cam for'yexerting a closing vpressure on ,themain 'jawsy andan antifriction member through which jthe-j awL closing force ofthe `cam is applied,. whereby u thecam'may be caused to' exert its maximum pressure owing:r tothe fact that the contactimg or operating friction of thec'am for elosin g the jaws, is reduced to 'the' minimum.

'i `The inventionV further consists the'pro- 2 vision'oflinks in` which the closing cam is mounted, said i. links being adapted to be swung down Lout ofthe waypermittingthe jaws to, swing to aj wide open. position to facilitate positioning the specimen inthe auxiliary jaw member. j

A` still fu .ther object "of the j invention is the provision of` means for "adjusting the links to determine the most `effectiveVoperrating position of the cam. `f j With these `and other objects in view, the invention consists of' certain novel features of construction, y as -will be "more `fully de- "scribed,'and particularlypointed out in the appended claims. "L In the accompanying drawings. j

Figure 1 is `a side` `elevation `of my improved combinationclamp and showingin dotted linesonejaw-` arm as being 'released by the camf'and swung downto wideopen position.

Figure Sis-a top viewof'the clamp. 5

``Figure a sectional s ideelevationillustrating the cam as exertmguts closlng force upon the `jaws throughaiball `bearing element, and showing va":fragmentary portion `of one of thejawcams.`

" Figure 4; is' a sectionalside elevation `show-A ing the caml operating means for adjusting the link `pivoted to regulate the operating poition of the cam mounted in itsopposite en.

p ,Figure f5'is`a`d'eta1l of the auxiliary tension jaw removed from the main clamp and showlng its biting jaw in open position.

It is found in practice in the `operation of machines for testing the strength or stretch of materials of advantage to apply `a uniform tension to each of the specimens lto be tested before the closing jaws of the main clamp upon them. 1

AThen again itV has been foundthat where cam lis employed for causing the clamp jaws to exert the necessary gripping pressure upon a specimen by directly engaging the jaw, that the sliding or rubbing friction of the cam is so great as to limit its effective action, and I have, therefore, eliminated this closing friction by mounting `the cam` to to compensate for wearof parts and varying thicknesses ofthe specimens being tested,

and the following isa detailed description of one means by which each of these results may be accomplishedzn With reference tothe drawings, l() desig4 lnates the main jaw arm of my improvedf clamp, which is preferably provided at its lowerend with a boss 11 to which the tension rod or member 121s secured and its upper end with a gripping faced member 13. j To the lower vportion of this main jaw arnrI havepivoted at `14 a swingingjaw arm15,'the same being provided with a gripping faced member 16 to cooperate with the corresponding member 13`on the main jaw, to grip the Vspecimen 17 to be tested between them.` This swinging jaw is provided with a spring `18 to normally press it to open position which is shown in dotted lines in Figure 1.

A pair of link members 19 `are pivoted `each on opposite sides of the main arm 10 on the pin 20 `and this pin is preferably provided with a cam portion 21 having a toothed outer surface as at 22 to be engaged by a worm 23 mounted on a shaft 24, the latterv being provided with a screw driver slotted end 25 by which it may be rotated to adjust the position of the cam 21 and so regulate the operating length of the links.

Between the outer or free ends of these links I have mounted a cam 26 on the shaft 'd 27 and have connected to this shaft an operating handle 28 whereby the cam may be rotated, and this handle is provided with a stop lug 29 adapted to rest against the face of the jaw 15 to limit the inward throw of the cam handle.

It has been found in practice that where the working face of the cam directly engages the face of the jaw that the sliding friction of moving one surface upon the other is so great as to limit the operating power of the cam, and to obviate this serious difliculty in the action of the cam, I have inclosed thel cam within a ball or anti-friction bearing, which in this instance comprises an outer raceway ring 30, an inner raceway ring 31 and a row of balls or rollers between the two. The inner ring being preferably shrunk on or otherwise connected to the cam face 26 while the outer ring is adapted to float and to engage the recessed portion 32 of the jaw 15 upon applying the closing pressure to the jaws whereby the clamping movement of the cam will cause the inner ring to rotate on the balls or anti-friction member while the outer ring will be retained by friction against rotation, by which construction the maximum closing power of the cam may be exerted on the jaws when pressure is applied to the operating handle.` By mounting this cam member in the free ends of the pivot links 19, upon swinging the camhandle outwardly the links are released to be dropped into the dotted position illustrated in Figure 1, toV permit the arm 15 to swing to its wide open position to facilitate positioning the specimen between the jaws of the lauxiliary preliminary tension weight 33, which Weight is provided with a weighted body port-ion 34 mounted to slide on a pair of vertical rods 35 in the main jaw arm 10 and this body portion is provide-d with a clamp jaw 36 pivoted at 37 and normally pressed to closed position by a spring 38. Y Y

In operating the clamp it is only necessary to throw the cam operating handle outwardly to permit the links to be dropped down into dotted position illustrated in Figure 1, when the pivot jaw 15 may be swung to wide open position. The lower end of the specimen 17 is then gripped by the jaw 36 of the weighted clamp 33 whereupon this clamp exerts a given tension upon each of the specimens alike before the jaws of the main clamp are closed upon them. It is now only necessary to raise the jaw 15 and the links with its cam u against the jaw and then by swinging tie cam handle 28 inward the clamp jaw is caused to firmly grip the specimen to be tested.

In order to compensate Vfor wear of the gripping parts to adjust for specimens of different thicknesses, it is only necessary to apply a screwdriver to the pin 24 to rotate The foregoing kdescription `is directed solel towards the construction illustrated, Y

but desire it to be understood that I reserve the privilege of resorting to all the mechanical changes to whichA the device'is susceptible, the invention being defined and limited only by the term of the appended claims.V

I claim; j y y l 1. A clamp having a. pair of relatively movable jaw members mounted to be separated for the reception of the iwork, a cam for exerting a closing force on said jaws, a ball bearing unit through which pressure yis applied by said cam tosaid members7 said unit comprising an inner shell fixed to said cam, an outer shell rotatable i relatively thereto, said shells being` groovedto provide a raceway kbetween them, `and anti-friction balls in said-,rawaythrough which pressure from one shell to the other is applied.

2. A- clamp having a pair .of lrelatively movable jaw members mounted torbe separated for the reception of the-work, a cam for exerting a closing force on said jaws, a ball bearing unit through which pressure is applied by said cam to said members,said unit having relatively rotatable inner" and outer portions, said inner portion xed to said cam and said outerportionengaging one of said jaw members, a handle for rotat-ing said cam whereby a closingpressure may Vbe exerted on said member without frictional sliding actionbetween said outer portion and its engaged jaw member.

3. A clamp havingv a pair of relatively movable jaw members mounted to be separated for the reception ofthe work, acam i for exerting a closing force on said jaws, an anti-friction unit having relatively rotatable inner and outer portions encircling said cam through which pressure is applied by said cam to the jaw members, anti friction means between said inner and outer portions, said inner portion fixed to said cam to movev therewith relatively to said outer portion over said anti friction means in the exerting of a closing pressure on said members. y

4. A clamp having one fixed and one movable jaw, a link pivoted at one end to said fixed jaw, a cam acting through said link for closinfr said jaws, a ball bearing element having re atively rotatable inner and outer portions with anti-friction balls therebetween encircling said cam and through which pressure is applied for closing said jaws, said inner and outer portions being fixed to said cam to move therewith relatively to said outer portion, and said link being movable about its pivot when said cam is in released position to permit the movable jaw to swing open for the reception of the work.

d0 5. A clamp having one fixed and one movable jaw, a link pivotedat one end to said fixed jaw, a cam carried by said-link, an anti-friction member on said cam and acting through said link for, closing said jaws, means whereby the link may be moved to withdraw the cam from operating position to ermit the movable jaw to swing to a wi e open position, and means for adjusting said 1in to regulate the operating position of said cam.

`6. A clamp having one fixed and one movable jaw, a' link, an adjustable eccentric through which said link is connected to said fixed jaw, cams mounted on the opposite ends of the link, and means for rotating said eccentric to adjust the relative operative position of said cam.

In testimony whereof I aix my signature.

HENRY L. SCOTT. 

